Printing disc having bifurcated type arms

ABSTRACT

A one-piece disc-shaped printing matrix for a serial printer, which matrix is adapted to be rotatably indexed to bring selected type elements thereon to a predetermined print position. The matrix is provided with a plurality of radially extending arms, each of which has at least two type-carrying fingers radially extending therefrom.

United States Patent 1191 1111 3,921,784 Orlens 1 Nov. 25, 1975 [54] PRINTING DISC HAVING BIFURCATED 3,356,199 12/1967 Robinson 197/54 TYPE ARMS 3,643,774 2/1972 Kondur, Jr 197/53 X 3,774,531 1l/l973 Hansen et al....., 101/111 X [75] Inventor: Alfreds Orlens, Old Greenwich,

Conn. FOREIGN PATENTS OR APPLICATIONS 601,956 2/1960 ltaly 197/53 1 Asslgneel ey-Bowes, Inc., Stamford, Conn. 454,899 3/1949 Canada 56/400.17 [22] Filed: Mar. 15, 1974 Primary ExaminerClifford D. Crowder PP N05 451,344 Attorney, Agent, or Firm-William D. Soltow, Jr.;

Albert W. Scribner; Martin D. Wittstein [52] US. Cl. 197/54; l97/6.7; 197/46 51 int. c1. B41J 1/32 [571 ABSTRACT [58] Field of Search 197/54, 53, 46, 6,7, 6.6, A one-piece disc-shaped printing matrix for a serial 197/18; 56/400.02, 400.03, 400.16, 400.17, printer, which matrix is adapted to be rotatably in- 400.18, 400.21; 101/109, 111, 112 dexed to bring selected type elements thereon to a predetermined print position. The matrix is provided [56] References Cited with a plurality of radially extending arms, each of UNITED STATES PATENTS which has at least two type-carrying fingers radially 1,239,687 9/1917 Hanamma 56/400.l7 extendmg therefrom 3,227,258 1/1966 Pannier et a1 197/54 X 3 Claims, 7 Drawing Figures PRINTING DISC HAVING BIFURCATED TYPE ARMS 2 BACKGROUND OF THE INVENTION The radial spokes or arms of conventional type printing discs or matrixes used in certain high speed serial printers are provided with typeelem'entsattheir respective free outer ends and in operation are deflected to a predetermined extent by a suitable hammer means so that said type elements are respectively brought into printing cooperation with a print receiving sheet. These cantilevered arms must be rigid enough to taccommodate the rapid angular acceleration and deceleration occurring during the rotational indexing of the'print disc. however they must also be flexible enough to be readily deflected during the above noted printing operations. The relatively high flexing stresses developed at the radially inner ends'of said arms during-printing and- /or indexing operations are apt to cause failure in this region, i.e., where the said arms are joined to the .central hub portion of the disc. For a'given outside diameter of a print disc, this maximum flexing stress may be excessively high where said arms are relatively short but may be reduced in some cases by making the arms longer; the latter being accomplished by reducing the effective diameter of the said central hub portion ofthe disc. When lengthening such however the cross sectional size and/or shape of the arms in said region may be decreased or otherwise changed so that the disc material in said region may become structurally weaker and thus less able to withstand the repeated flexing stresses occurring during successive indexing and printing operations.

SUMMARY OF THE INVENTION bers of a print disc whereby the maximum flexing.

stresses developed during bending of a print arm through a given distance are minimized to the point where the chance of breakage or failure of the arms is substantially eliminated. To this end each arm of the instant print disc is given a bifurcated construction whereby the radial outer portion of each arm carries at least two radially extending type-supporting fingers. Further the axial thickness of each arm is increased in the region where its associated fingers join the arm, and each finger is made longer than its associated arm in order to efficiently distribute the stresses existing in each arm as the latter is flexed.

The primary object of the instant invention is to provide a novel disc-shaped print matrix which is relatively inexpensive to produce and which is light and rigid enough for effective use in high speed serial printers.

A further object of the invention is to provide a novel construction and arrangement for a print disc whereby the maximum operational flexure stresses in the radial arms thereof may be kept at relatively low values.

In the drawings:

FIG. 1 is a front elevational view illustrating a con ventional type print matrix.

FIG. 2 is a cross sectional view taken along section line 2-2 of FIG. 1.

FIG. 3 is a front elevational view illustrating another conventional type matrix that is similar to that shown in FIG. 1.

' portion 11 from, which radially extend a plurality of integral flexible cantilever arms l2, each arm carrying a type element 13 at the freeouter end thereof. The

width of each arm 12, as seen in, FIG..1, is substantially uniform throughout the radial length thereof. In operation the disc 10 is adapted to be rotatably indexed about its axis R, FIG. 2, to bring a selected type elemerit to apredetermined print position after which a suitable hammer action, indicated by arrow 14, FIG. 2, serves to deflect the selected type element through a predetermined fixed distance d and into operative printing engagement with the usual printribbon-and print receiving paper indicated generally by reference 'numeral 15. As will be apparent any bending of the arms 12 occurring during said indexing and printing actions will produce relatively high'flexure stresses in the disc material in the region 17 where eachcantilever I a value of 1 asshown in FIG. 1 to a value of 1 as shown for the print matrix 11a of FIG. 3, this being ac- I complished by increasing the-depth ofthe radial slots 18, FIG. 3, between said arms 12a. This effective lengthening of arms 12a, FIG. 3, can help to some extent to reduce the maximum operational stresses developed in region 17a during said indexing movement and- /or during said given arm deflection (1 FIGS. 2 and 4; however there is a limit to how much the arms can be so lengthened because as the diameter of the hub portion 11a is here reduced the width, as seen in FIG. 3, of the base region 17a of each arm may also have to be narrowed due to the reduced circumferential length of hub portion 11a. Such a narrowing of the effective width of the inner ends of the arms 12a will reduce the cross sectional shape and/or size of the base of said arms and this in turn will reduce the arm rigidity or strength required to accommodate the angular accelerations and decelerations of the disc and the print flexure of said arms. It will be apparent then that what stress advantages may be initially obtained by lengthening the arms may quickly be lost by the stress disadvantages that accompany a narrowing of the base of said arms 12a.

The present invention contemplates obtaining the stress advantages of lengthening said arms without incurring the above noted disadvantages normally incident thereto. Referring to FIGS. 5, 6 and 7, there is shown a one-piece print disc 20 which is molded from a suitable plastic material such as Delrin and which includes a central hub portion 21 having a plurality of integral arms 22 radially extending therefrom. The outer end of each arm is integrally formed with a pair of radially extending fingers 23; the arm region at the base of each pair of fingers being axially thickened and reinforced as illustrated at 24 of FIG. 6. Suitably secured to the free outer end of each finger 23 is a type element 26, a circular array of type elements thus being formed. For discussion purposes each of the print discs 10, a and are here considered to have the same effective outside radius r The width of each finger 23 as seen in FIG. 5, is substantially uniform throughout its length and is substantially equal to the corresponding width w of the radial inner portion of the associated arm 22. Each finger 23 is made as long as possible, and preferably is longer than its associated arm 22. The effective radial length 1 FIG. 5, for each composite cantilever support for type elements 26 is shown equal to the corresponding arm length 1 for the disc 10a of FIG. 3 and is effectively defined by the combined radial length of the associated finger 23 and arm 22. Here however there are only half as many arms 22 as type elements 26 so that the said width w of said arms 22 may now be made substantially greater than the corresponding width of arms 12a, FIG. 3, which in turn will insure that only relatively low operational flexure stresses are developed in the region 25 where arms 22 connect with the hub portion 21. Thus the advantages of a lengthened cantilever support for each type element are obtained here without otherwise incurring the usual accompanying disadvantage of high stress development at the base of the type support arms.

In operation, the type disc 20 is adapted to be rotatably indexed about its axis R FIG. 6, to bring a selected type element to a predetermined print position. After each disc indexing step an associated hammer action, indicated at 30, will cause the selected type element, such as 26x, to be displaced through the same predetermined fixed distance d to a print position as illustrated in said FIG. 7. During this printing action the adjacent type element 26y supported on the same arm as type element 26x is simultaneously displaced through a relatively short distance towards said print receiving sheet 15, this short displacement however being insufficient to produce any printing action by the type element 26y.

By utilizing the above described construction and arrangement for disc 20 the arms 22 thereof may be made rigid enough to accommodate rapid rotational indexing motion occurring during high speed serial printer operations and yet may be flexible enough to be readily deflected to print positions without developing high flexure stresses at the inner ends of said arms. These advantageous features will impart to the print disc 20 a long reliable operational life devoid of mechanical failures or breakages.

What is claimed is:

l. A rotative printing disc for use in a high speed serial printer, said printing disc adapted to be rotatively movable so as to be indexed to any one of several select print positions; said printing disc comprising a central hub portion and a plurality of arms carried by, and substantially radially extending from, said hub portion; each of said arms being bifurcated to provide a pair of outwardly extending type supporting fingers, each of said fingers having an outer end; a separate type element mounted on each of said outer ends; and each finger of each pair of the outwardly extending type supporting fingers being longer than its respective arm.

2. The rotative printing disc of claim 1, wherein said arms and fingers are reinforced by an enlarged section in a region defining the bifurcation of said arms.

3. The rotative printing disc of claim 1, wherein said arms and said fingers are disposed in a substantially 

1. A rotative printing disc for use in a high speed serial printer, said printing disc adapted to be rotatively movable so as to be indexed to any one of several select print positions; said printing disc comprising a central hub portion and a plurality of arms carried by, and substantially radially extending from, said hub portion; each of said arms being bifurcated to provide a pair of outwardly extending type supporting fingers, each of said fingers having an outer end; a separate type element mounted on each of said outer ends; and each finger of each pair of the outwardly extending type supporting fingers being longer than its respective arm.
 2. The rotative printing disc of claim 1, wherein said arms and fingers are reinforced by an enlarged section in a region defining the bifurcation of said arms.
 3. The rotative printing disc of claim 1, wherein said arms and said fingers are disposed in a substantially common plane. 